Quad Classic ll 40 amps - Tube rolling/biasing?

I've just brought a pair of classic 40 amps and although I love the sound I'm considering upgrading the Kt88 Sovtek's. The manual says tube changes should be done by the dealer or Quad service and says nothing about biasing etc.
Does anybody have any experience of tube rolling these amps and the bias settings/requirements


Can't comment on the biasing.For KT-88s,I would get the Shuguangs.Very linear with good timbre.If you like the sound of the Sovtek,then you might also consider the Gold Lion re-issue.IMO,I prefer the Chinese to russian tubes.
I just bought the same set of monoblocks from Caxton Audio in Brisban. Enquired about biasing and whether or not directions are included for biasing and so on. They bias automatically. Assume you bought these from Simply Hi Fi. Ask Win. He's usually quite good about info and advice. Also, as part of the deal, I bought a quad of the Genalex Gold Lion KT88s. I currently use the same Gold Lions in a conrad-johnson MV-60SE amp (that has been converted to triode mode). They are very wonderful tubes.

I would be tempted to upgrade the 6SH7s as well. If you e-mail me, I might be able to help you out there.
Hello Bannister,

Thanks for your response.

I finished up getting the info from Quad about just dropping a new set without the need to re-bias. We brought a QUAD set of Svetlana Winged C - Crio treated. Very Impressed.

The amps don't actually belong to me, but I've been loaned them for a few months while a friend is OS and enjoying them immensely.

The 6SH7s are Philips in one amp and GEC in the other. Not sure about the need to match? Not much on the web about this.

Do yours run hot. I seem to be getting a lot of heat building up in the main transformer (casing) - one more than the other.

Also they have 5AR4 rectifier tubes not the 5UAG as listed in the specs. I queried QUAD in the Uk about this - and although they've never used these, they said there shouldn't be a problem.